1盏缤、MarkPass的作用：

可以對指定的scene運(yùn)行后期效果。

2辨泳、效果圖：

3虱岂、使用步驟：

3.1、引入文件

import { RenderPass } from '../../node_modules/three/examples/jsm/postprocessing/RenderPass';
import { ShaderPass } from '../../node_modules/three/examples/jsm/postprocessing/ShaderPass';
import { ClearMaskPass, MaskPass } from 'three/examples/jsm/postprocessing/MaskPass';
import { CopyShader } from 'three/examples/jsm/shaders/CopyShader';

3.2菠红、過程概述：

（1）創(chuàng)建一個作為背景圖片的場景第岖。
（2）創(chuàng)建一個場景，里面包含一個看起來像地球的球體试溯。
（3）創(chuàng)建一個場景蔑滓，里面包含一個看起來像火星的球體。
（4）創(chuàng)建EffectComposer對象，用于將這三個場景渲染到一個圖片中键袱。
（5）在渲染為火星的球體上應(yīng)用彩色效果燎窘。
（6）在渲染為地球的球體上應(yīng)用褐色效果。

3.3蹄咖、注意事項：

1褐健、 我們直接使用場景的背景屬性來添加星光背景圖片。還有一種可選方式也可以同于添加背景圖片澜汤，那就是利用THREE.OrthoGraphicCamera（正交攝像機(jī)）蚜迅。因為THREE.OrthoGraphicCamera不會根據(jù)物體距離攝像機(jī)的距離來縮放物體，所以可以添加一個正對攝像機(jī)的THREE.PlaneGeometry幾何體银亲，然后在上面添加圖片慢叨。
2、場景渲染時候需要將渲染器改為組合器的渲染器务蝠，并且需要將WebGLRenderer中autoClear設(shè)置為false

4拍谐、完整源代碼：

import { OrthographicCamera, Vector3, Scene, WebGLRenderer, Color, SphereGeometry, MeshPhongMaterial, TextureLoader, Mesh, Clock, AmbientLight, DirectionalLight, PlaneGeometry, MeshBasicMaterial, PerspectiveCamera } from 'three';
import { RenderPass } from '../../node_modules/three/examples/jsm/postprocessing/RenderPass';
import { ShaderPass } from '../../node_modules/three/examples/jsm/postprocessing/ShaderPass';
import { ClearMaskPass, MaskPass } from 'three/examples/jsm/postprocessing/MaskPass';
import { CopyShader } from 'three/examples/jsm/shaders/CopyShader';
import { OrbitControls } from '../../node_modules/three/examples/jsm/controls/OrbitControls';
import { SepiaShader } from '../../node_modules/three/examples/jsm/shaders/SepiaShader';
import { ColorifyShader } from '../../node_modules/three/examples/jsm/shaders/ColorifyShader';
import { EffectComposer } from 'three/examples/jsm/postprocessing/EffectComposer';
export class Effect {
    private sceneEarth!: Scene;
    private sceneMars!: Scene;
    private sceneBG!: Scene;
    private cameraBG!: OrthographicCamera;
    private camera!: PerspectiveCamera;
    private webGLRenderer!: WebGLRenderer;
    private earthSphere!: Mesh;
    private marsSphere!: Mesh;
    private earthMaterial!: MeshPhongMaterial;
    private marsMaterial!: MeshPhongMaterial;
    private clock !: Clock;
    private ambEarth!: AmbientLight;
    private ambMars!: AmbientLight;
    private dirEarth!: DirectionalLight;
    private dirMars!: DirectionalLight;
    private bgPass!: RenderPass;
    private earthPass!: RenderPass;
    private marsPass!: RenderPass;
    private composer!:EffectComposer;
    constructor() {
        this.clock = new Clock();
        // 創(chuàng)建三個場景
        this.sceneEarth = new Scene();
        this.sceneMars = new Scene();
        this.sceneBG = new Scene();

        // 相機(jī)設(shè)置
        this.camera = new PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
        this.camera.position.x = -10;
        this.camera.position.y = 15;
        this.camera.position.z = 25;
        this.camera.lookAt(new Vector3(0, 0, 0));

        this.cameraBG = new OrthographicCamera(-window.innerWidth, window.innerWidth, window.innerHeight, -window.innerHeight, -10000, 10000);
        this.cameraBG.position.z = 50;

        // 渲染器設(shè)置
        this.webGLRenderer = new WebGLRenderer({ antialias: true });
        this.webGLRenderer.setClearColor(0x000000, 1.0); //設(shè)置背景顏色
        this.webGLRenderer.setSize(window.innerWidth, window.innerHeight);
        this.webGLRenderer.setPixelRatio(window.devicePixelRatio);
        this.webGLRenderer.shadowMap.enabled = true;
        document.body.appendChild(this.webGLRenderer.domElement);

        // 地球
        this.earthSphere = this.createEarthMesh(new SphereGeometry(10, 40, 40));
        this.earthSphere.position.x = -10;
        this.sceneEarth.add(this.earthSphere);
        // 火星
        this.marsSphere = this.createMarshMesh(new SphereGeometry(5, 40, 40));
        this.earthSphere.position.x = 20;
        this.sceneMars.add(this.marsSphere);

        // 環(huán)境光
        this.ambEarth = new AmbientLight(0x181818);
        this.sceneEarth.add(this.ambEarth);
        this.ambMars = new AmbientLight(0x181818);
        this.sceneMars.add(this.ambMars);

        // 方向光
        this.dirEarth = new DirectionalLight(0xffffff, 0.6);
        this.dirEarth.position.set(550, 100, 550);
        this.sceneEarth.add(this.dirEarth);

        this.dirMars = new DirectionalLight(0xffffff, 0.6);
        this.dirMars.position.set(550, 100, 550);
        this.sceneMars.add(this.dirMars);

        // 背景平面
        const bgPlane = new PlaneGeometry(1, 1);
        const bgPlaneMaterial = new MeshBasicMaterial({
            map: new TextureLoader().load('../assets/starry-deep-outer-space-galaxy.jpg'),
            depthTest: false // 不啟動深度測試即設(shè)置成false就擁有類似透視的效果

        });
        const bgMesh = new Mesh(bgPlane, bgPlaneMaterial);
        bgMesh.position.z = -100;
        bgMesh.scale.set(window.innerWidth * 2, window.innerHeight * 2, 1);
        this.sceneBG.add(bgMesh);

        // 后期處理
        //RenderPass根據(jù)scene和camera渲染出一個場景，和普通的webGLRenderer一樣
        this.bgPass = new RenderPass(this.sceneBG, this.cameraBG);
        // this.bgPass.clear = false;
        this.earthPass = new RenderPass(this.sceneEarth, this.camera);
        this.earthPass.clear = false;//if set to true, the pass clears its buffer before rendering
        this.marsPass = new RenderPass(this.sceneMars, this.camera);
        this.marsPass.clear = false;
        
        const effectCopy = new ShaderPass(CopyShader);
        effectCopy.renderToScreen = true;

        const clearMark = new ClearMaskPass();
        // earth mark
        const earthMark = new MaskPass(this.sceneEarth, this.camera);
        // earthMark.inverse = true;

        //mars mark
        //sceneMask和clearMask可以理解成ps圖層的透明部分馏段。不添加mask轩拨，效果就應(yīng)用到整個場景，添加了就只應(yīng)用到場景中的物體院喜，用完記得需要清除亡蓉。
        //掩碼的作用:可以對指定的scene運(yùn)行后期效果
        const marsMark = new MaskPass(this.sceneMars, this.camera);

        const effectSepia = new ShaderPass(SepiaShader);//烏賊墨效果
        effectSepia.uniforms['amount'].value = 0.8;

        const effectColorify = new ShaderPass(ColorifyShader);//整個顏色覆蓋屏幕
        effectColorify.uniforms['color'].value.setRGB(0.5, 0.5, 1);

        // 組合通道
        this.composer = new EffectComposer(this.webGLRenderer);
        //需要注意的是需要將使用掩碼前，要將composer.renderTarget.stencilBuffer設(shè)置為true,用于限制渲染區(qū)域喷舀。
        //另外砍濒，使用完掩碼后，需要使用ClearMaskPass()去掉掩碼區(qū)域
        this.composer.renderTarget1.stencilBuffer = true;
        this.composer.renderTarget2.stencilBuffer = true;

        this.composer.addPass(this.bgPass);
        this.composer.addPass(this.earthPass);
        this.composer.addPass(this.marsPass);
        //掩碼的作用:可以對指定的scene運(yùn)行后期效果
        this.composer.addPass(marsMark);//添加掩碼硫麻，后續(xù)通道只會影響掩碼區(qū)域爸邢，取消掩碼需要加入THREE.ClearMaskPass通道
        this.composer.addPass(effectColorify);
        this.composer.addPass(clearMark);
        this.composer.addPass(earthMark);
        this.composer.addPass(effectSepia);
        this.composer.addPass(clearMark);
        this.composer.addPass(effectCopy);


        const orbitControls= new OrbitControls(this.camera, this.webGLRenderer.domElement);
        orbitControls.autoRotate =false;

        window.addEventListener('resize', ()=>this.onWindowResize());
        this.render();
    }
    private onWindowResize() {
        this.webGLRenderer.setSize(window.innerWidth, window.innerHeight);
        this.camera.aspect = window.innerWidth/window.innerHeight;
        this.camera.updateProjectionMatrix();

        this.cameraBG.left = -window.innerWidth;
        this.cameraBG.right = window.innerWidth;
        this.cameraBG.top = window.innerHeight;
        this.cameraBG.bottom = -window.innerHeight;
        this.cameraBG.updateProjectionMatrix();
    }
    private render() {
        this.webGLRenderer.autoClear = false;//一定要設(shè)置
        window.requestAnimationFrame(() => this.render());
        this.earthSphere.rotation.y+=0.02;
        this.marsSphere.rotation.y+=0.02;
        this.composer.render(this.clock.getDelta());//參數(shù)設(shè)置成兩幀間隔時間
    }
    private createMarshMesh(geom) {

        this.marsMaterial = new MeshPhongMaterial({
            map: new TextureLoader().load('../assets/Mars_2k-050104.png'),
            normalMap: new TextureLoader().load('../assets/Mars-normalmap_2k.png')
        });
        const mesh = new Mesh(geom, this.marsMaterial);
        return mesh;
    }

    private createEarthMesh(geom) {
        this.earthMaterial = new MeshPhongMaterial({
            map: new TextureLoader().load('../assets/Earth.png'),
            specularMap: new TextureLoader().load('../assets/EarthSpec.png'),
            normalMap: new TextureLoader().load('../assets/EarthNormal.png'),
            specular: new Color(0x4444aa)
        });
        const mesh = new Mesh(geom, this.earthMaterial);
        return mesh;
    }
}